Burglar alarm



FIG. 1 is a front view in elevation of a burglar alarm embodying the present design;

FIG. 2 is a left side view in elevation of the same burglar alarm;

FIG. 3 is a plan view of the same burglar alarm; and

FIG. 4 is a bottom view of the same burglar alarm. 

The ornamental design for a burglar alarm, substantially as shown. 